1. Field of the Invention
The present invention relates to a method for collecting opinions of push-to-talk-cellular (PoC) participants in a PoC network.
2. Description of the Related Art
Significant developments in mobile communications technology and the extension of mobile communications networks have resulted in the development of a vast array of services and applications for use with a cellular phone. At the same time, demand among cellular phone users for these additional services, such as a location, multimedia and a push-to-talk (PTT) service, is increasing. The PTT service supports various supplementary functions such as an instant messenger function and a status display function, as well as a group call and a voice call which are also provided by an existing radio or a trunk radio system (TRS).
Currently, standardization of a push-to-talk-over-cellular (PoC) service that employs the PTT function in a mobile communication network is taking place. A unique feature of the PoC service is that a user can participate in a plurality of PoC sessions and can also use a call service while switching from the PoC sessions as desired. This feature is a requirement that is specified in the open mobile alliance (OMA), which is a forum for specifying mobile communications services.
FIG. 1 is a schematic diagram of a conventional PoC service system. Referring to FIG. 1, a PoC client 10, as a service requester installed in a mobile station, is generally connected to a Session Initiation Protocol/Internet Protocol (SIP/IP) core 30 that supports SIP and IP multimedia via an access network 20.
The PoC client 10 resides in a PoC user terminal to provide access to the PoC service. The PoC client 10 mainly serves to establish, participate in and terminate a PoC session. In addition, the PoC client 10 makes and transfers a talk burst, supports an instant personal alert and performs authentication when accessing the PoC service. Hereinafter, unless otherwise stated, the PoC client 10 and PoC user are assumed to be the same as a PoC service subscriber.
The SIP/IP core 30 is connected to a PoC server 60, a Group List and Management System (GLMS) 50 and a presence server 70 in order to support the PoC service.
The PoC server 60 has a Controlling PoC Function for maintaining and managing a PoC session, or a Participating PoC Function for participating in a PoC session for a one-to-one PoC call or a one-to-two or more PoC call (or group PoC call).
Functional blocks in the PoC server will be described with reference to FIG. 2, a schematic diagram showing the configuration of a conventional PoC server.
The PoC server performs both a Controlling PoC Function (hereinafter “CF”) of controlling overall maintenance and management of a PoC session and the Participating PoC Function (hereinafter “PF”) of controlling maintenance and management between each PoC session, which will be explained below with reference to Tables 1 and 2.
TABLE 1Controlling PoC Function (CF)Provides centralized PoC session handlingProvides centralized Media distributionProvides centralized Talk Burst Arbitration functionalityincluding talker identificationProvides SIP session handling, such as SIP session origination,termination, etc.Provides policy enforcement for participation in group sessionsProvides participant informationCollects and provides centralized media quality informationProvides centralized charging reportsMay provide transcoding between different codecsSupports Talk Burst Control Protocol Negotiation
As shown in Table 1, the PoC server performing the CF (or the Controlling PoC server) serves to manage a PoC session. In particular, the Controlling PoC server receives requests for the floor from PoC clients, arranges an order in which to give the clients the floor, and gives the clients the floor in that order. The Controlling PoC server also distributes a talk burst, for which an arbitrary PoC client makes a request, to all other PoC clients participating in a group PoC call, and provides information of the PoC clients participating in the group PoC call.
As shown in Table 2 below, the PoC server performing the PF (or the Participating PoC server) manages a PoC session between the Controlling PoC server and each PoC client. In particular, the Participating PoC server acts to relay the floor between the PoC client and the Controlling PoC server when the PoC client makes a request for the floor or when the Controlling PoC server gives the floor to the PoC client. In addition, the Participating PoC server relays media between the Controlling PoC server and the PoC client, performs transcoding between different codecs, and filters one of two concurrent PoC sessions according to the choice of a PoC user when there is simultaneous talking in the two active PoC sessions.
TABLE 2Participating PoC Function (PF)Provides PoC session handlingMay provide the Media relay function between PoC client andControlling PoC serverMay provide user media adaptation proceduresMay provide the Talk Burst control message relay function betweenPoC client and Controlling PoC serverProvides SIP session handling, such as SIP session origination,termination, etc, on behalf of the represented PoC client.Provides policy enforcement for incoming PoC session (e.g. accesscontrol, incoming PoC session barring, availability status, etc.)May collect and provide media quality informationProvides participant charging reportsMay provide filtering of media streams in the case ofsimultaneous sessionsMay provide transcoding between different codecsMay support Talk Burst Control Protocol NegotiationStores the current Answer Mode and Incoming PoC Session Barringpreferences of the PoC client
In the PoC service system described above, the PoC user can input information on groups and their members into the GLMS 50 through the PoC user's terminal, and can receive information about other PoC users with whom the PoC user can talk through an individual or group list transmitted from the GLMS 50. Alternatively, in order to create, modify and manage groups and their members, the information on the groups and their members may be input into the GLMS 50 via a communication network, such as an Internet or Intranet.
In order to use the PoC call service, the PoC user registers his/her PoC address with the SIP/IP core 30. The SIP/IP core 30 stores information on the PoC user by request of the PoC user. Thus, when another PoC user tries to request the group PoC call, the PoC user registers his/her information with the SIP/IP core 30 in advance, and requests the group PoC call to his/her SIP/IP core 30 by using group identification information transmitted from the GLMS 50. At this time, the SIP/IP core 30 performs addressing and domain locating by using information of the requesting PoC user and then transfers a PoC call request to a home PoC server with which the requesting PoC user is registered. In regard to the PoC call request, the PoC server prepares to establish a PoC session, obtains each user's information from the GLMS 50, and then transfers a PoC call request signal to the SIP/IP core. When a PoC call request is made to users within an Intradomain, the PoC server performs both the CF and the PF. The PoC server managing the call-requested PoC user requests the PoC call to the PoC user after locating the SIP/IP core 30 by using the PoC user's information transmitted to the PoC server.
FIG. 3 is a schematic diagram illustrating CF and PF blocks of a PoC server. Referring to FIG. 3, PoC clients 111, 121, 131 and 141 provide access to a CF 100 through PFs 110, 120, 130 and 140 respectively, thereby establishing a PoC session. Here, when a floor is granted to a requester qualified as a talker from the CF 100, media based on speaking of the corresponding PoC client is transmitted to each PoC client.
FIG. 4 is a signaling flow for a conventional procedure where a PoC user obtains a floor.
Referring to FIG. 4, in order to obtain a floor, a PoC client A 111 presses a PoC talk button installed to his/her own PoC terminal when no PoC client is talking within a PoC session where the PoC client A 111 is connected to a PoC client B 121.
Therefore, the PoC client A 111 transmits a Talk Burst Request message (S101) requesting the floor, to a PF A 110 acting as the Participating PoC Function. Thus, the PF A 110 transmits the Talk Burst Request message (S101) to a CF 100, a Controlling PoC server, acting as Controlling PoC Function of this PoC session.
After receiving the Talk Burst Request message (S101), the CF 100 transmits a Talk Burst Confirm Response message (S102) notifying that the floor is granted, to the PoC client A 111 as well as a Receiving Talk Burst from User A message (S103) to the PoC client B 121. Since the latter message includes an identifier (ID) of the PoC client A 111 who is qualified as the talker, the PoC client B 121 knows identity of the talker.
Then, a media session is opened, and a talk burst media (S104) is transmitted from the PoC client A 111 to the PoC client B 121.
However, the foregoing conventional art considers opinions of all persons requesting the floor when an attempt is made to hear and collect all of the opinions in the group PoC call. Hence, all procedures associated with such instances as a time to grant the floor and a time to propose the opinion when the floor is granted, are performed as many times as the number of group members. As such, the procedure is complicated and too much time is expended.